Comprehensive and accurate molecular profiling on a single-cell level is highly sought after within the fields of cell biology, pathology, and clinical diagnostics, especially for untangling the complex interactions underlying cancer, neurological disorders, and immune system disorders. A key challenge is presented by the complexity and heterogeneity of these diseases (Liu, A. Y., M. P. Roudier, and L. D. True, Heterogeneity in primary and metastatic prostate cancer as defined by cell surface CD profile. American Journal of Pathology, 2004. 165(5): p. 1543-1556 and True, L. D. and X. Gao, Quantum dots for molecular pathology: their time has arrived. J Mol Diagn, 2007. 9(1): p. 7-11), which is hard to assess using conventional biomedical techniques that suffer from a limitation in the number of biomarkers that can be analyzed simultaneously, provide limited single-cell information, and often utilize qualitative rather than quantitative analysis. See for example, Englert, C. R., G. V. Baibakov, and M. R. Emmert-Buck, Layered expression scanning: rapid molecular profiling of tumor samples. Cancer Research, 2000. 60(6): p. 1526-30; Furuya, T., et al., A novel technology allowing immunohistochemical staining of a tissue section with 50 different antibodies in a single experiment. Journal of Histochemistry and Cytochemistry, 2004. 52(2): p. 205-10; Glass, G., J. A. Papin, and J. W. Mandell, SIMPLE: a sequential immunoperoxidase labeling and erasing method. Journal of Histochemistry and Cytochemistry, 2009. 57(10): p. 899-905; Pirici, D., et al., Antibody elution method for multiple immunohistochemistry on primary antibodies raised in the same species and of the same subtype. Journal of Histochemistry and Cytochemistry, 2009. 57(6): p. 567-75; Schwamborn, K. and R. M. Caprioli, Molecular imaging by mass spectrometry—looking beyond classical histology. Nature Reviews. Cancer, 2010. 10(9): p. 639-46; Toth, Z. E. and E. Mezey, Simultaneous visualization of multiple antigens with tyramide signal amplification using antibodies from the same species. Journal of Histochemistry and Cytochemistry, 2007. 55(6): p. 545-54; Wahlby, C., et al., Sequential immunofluorescence staining and image analysis for detection of large numbers of antigens in individual cell nuclei. Cytometry, 2002. 47(1): p. 32-41; and Wollscheid, B., et al., Mass-spectrometric identification and relative quantification of N-linked cell surface glycoproteins. Nature Biotechnology, 2009. 27(4): p. 378-86. Consequently, fundamental understanding of pathological processes as well as clinical diagnostics are limited by the lack of knowledge about the predictive biomarkers that would unambiguously discriminate between disease and normal function, distinguish different disease types, and provide information about possible progression of the pathological process.
Advances in nanotechnology have enabled the design of nanoparticle-based tools for improved molecular characterization of physiological and pathological processes. In particular, semiconductor fluorescent nanoparticles (quantum dots, or QDs) have emerged as a new platform for high-throughput quantitative characterization of multiple biomarkers in cells and clinical tissue specimens (Zrazhevskiy, P. and X. Gao, Multifunctional Quantum Dots for Personalized Medicine. Nano Today, 2009. 4(5): p. 414-428 and Zrazhevskiy, P. and X. Gao, Quantum dots for cancer molecular imaging. Minerva Biotecnologica, 2009. 21(1): p. 37-52). Having size of only 2 to 10 nm in diameter, QDs possess unique photo-physical properties drastically different from those of single atoms or bulk materials. Size-tunable and spectrally narrow light emission, simultaneous excitation of multiple colors, improved brightness, resistance to photobleaching, and large Stokes shift enable simultaneous parallel detection and reliable quantification of up to 10 spectrally distinct QD probes Alivisatos, A. P., Perspectives on the physical chemistry of semiconductor nanocrystals. Journal of Physical Chemistry, 1996. 100(31): p. 13226-13239; Alivisatos, A. P., Semiconductor clusters, nanocrystals, and quantum dots. Science, 1996. 271(5251): p. 933-937; Bruchez, M., Jr., et al., Semiconductor nanocrystals as fluorescent biological labels. Science, 1998. 281(5385): p. 2013-6; Chan, W. C., et al., Luminescent quantum dots for multiplexed biological detection and imaging. Curr Opin Biotechnol, 2002. 13(1): p. 40-6; and Gao, X. and S. Nie, Molecular profiling of single cells and tissue specimens with quantum dots. Trends Biotechnol, 2003. 21(9): p. 371-3). However, utilization of such multiplexing capability has been hampered by the inability to uniquely match each QD probe with the corresponding biomarker, thus yielding simultaneous detection of only a modest number of biomarkers. See for example, Chen, C., et al., Quantum-dot-based immunofluorescent imaging of HER2 and ER provides new insights into breast cancer heterogeneity. Nanotechnology, 2010. 21(9): p. 095101; Fountaine, T. J., et al., Multispectral imaging of clinically relevant cellular targets in tonsil and lymphoid tissue using semiconductor quantum dots. Modern Pathology, 2006. 19(9): p. 1181-91; Ghazani, A. A., et al., High throughput quantification of protein expression of cancer antigens in tissue microarray using quantum dot nanocrystals. Nano Letters, 2006. 6(12): p. 2881-6; Huang, D. H., et al., Comparison and Optimization of Multiplexed Quantum Dot-Based Immunohistofluorescence. Nano Research, 2010. 3(1): p. 61-68; Liu, J., et al., Multiplexed detection and characterization of rare tumor cells in Hodgkin's lymphoma with multicolor quantum dots. Analytical Chemistry, 2010. 82(14): p. 6237-43; Liu, J., et al., Molecular mapping of tumor heterogeneity on clinical tissue specimens with multiplexed quantum dots. ACS Nano, 2010. 4(5): p. 2755-65; Shi, C., et al., Quantum dots-based multiplexed immunohistochemistry of protein expression in human prostate cancer cells. European Journal of Histochemistry, 2008. 52(2): p. 127-34; Sweeney, E., et al., Quantitative multiplexed quantum dot immunohistochemistry. Biochemical and Biophysical Research Communications, 2008. 374(2): p. 181-6; Wu, X., et al., Immunofluorescent labeling of cancer marker Her2 and other cellular targets with semiconductor quantum dots. Nat Biotechnol, 2003. 21(1): p. 41-6; and Yezhelyev, M. V., et al., In situ molecular profiling of breast cancer biomarkers with multicolorquantum dots. Advanced Materials, 2007. 19(20): p. 3146-3151.
Accordingly, there is need in the art for compositions and methods for multiplex detection, identification or quantitation of analytes in sample. This disclosure provides such compositions and methods.